Delve into differentiating ground loop interference from feedback within sound systems.
Effective strategies for combating ground loop noise include outlet verification, grounding devices lacking proper grounding, and ensuring all equipment shares a common ground source. By systematically disconnecting mixer connections, potential noise sources can be identified and resolved, crucial for achieving superior sound quality.
Hi, I'm David Lee from BASSBOSS. And today we're going to talk about everybody's favorite subject, ground loop noise.
First thing to understand is what's the difference between a ground loop and feedback? Feedback is a situation where the output of a system is looping back into it somewhere and it's creating a positive loop. In other words, what loops back in then gets amplified, is picked back up again, is amplified again, and that's where you get the runaway feedback. It requires the completion of that loop in the sense that you have to have an open microphone or something that's picking up the noise, maybe a turntable needle, some kind of instrument pickup, that kind of thing. So the sound coming into the environment is being picked up or vibration, whatever it is, being picked up, going back into the system and then being amplified. And that's feedback.
Ground loops are different in that they don't loop and amplify and feedback. A ground loop is not a feedback loop. What it is that noise is a noise. Usually it's electrical. Hum. 60 Hz hum can be other noise, noise that's created by motors or dimmers or that kind of thing that can get into the electrical system. But the pattern is that that electrical field is being generated and it's being induced into the signal cable, so that the signal cable is then on its own picking up that noise and feeding it forward into whatever gear. Eventually gets to the amplifiers and loudspeakers. And that's where you hear it. While it's not specific information to chasing ground loops or eliminating them, there are some practices that you should follow as a general rule: connect everything in sequence from the last to the first, so you can track the wiring flow back to the source.
Sometimes you'll find some gear, if it's not switched on, obviously not amplified gear, but front-end gear processors, things like that. If they're not powered up, if they don't have the power going to them, they will be more susceptible to noise once they're powered up. The noise can be eliminated. So don't chase ground loop noise on gear that hasn't been powered up yet. Wait until you got everything powered up. You want to power up your gear so that the last thing you actually turn on is the amplified gear. So the speakers or amplifiers need to go on last that way. Anything that makes a noise further up the signal chain won't make it to the speakers and make a pop.
Now if you have a noise, if you have a ground loop, there are some things you don't want to do. The first thing you don't want to do is start to eliminate grounds. People have a long time used these little adapters that were originally made for adapting modern equipment to old houses that only had two-pin plugs in them. And so it has the proper use of it. It actually has the two pins and then a little tab that you're supposed to connect via the screw that holds the cover plate on to ground too that people use them to eliminate ground. Now, if we get rid of the ground, there won't be a ground loop. This is not a good idea because the ground is there as a safety mechanism in case something else is wrong. It prevents that power from backing up through you in particular. So don't eliminate grounds that are on pieces of gear that have it, and you're much better off adding ground to pieces of gear that don't have it than you are eliminating ground because grounds are there as a safety mechanism and they should be maintained. They're there, they're important. When they're working properly, they don't cause the noise. This noise is coming from somewhere else. So eliminating ground is a dangerous cheat and it's not a good plan.
So how do you avoid ground loop noise? Step one, verify your outlets. It's just a good idea to do that. I mean, generally speaking, if it's the first time you're in a venue, it's worth it. You can get outlet checkers for anywhere between $5 and $45. So take your pick. They will tell you that you're good to go and you don't have so much to worry about. Generators also, if anybody's wiring up distros have one of those handy, a voltage meter is also a good thing to have, particularly with generators, because they do vary more than the grid. But an outlet checker will tell you that the things are wired the way they're supposed to be for your gear to be powered properly. In the simplest scenario, you have a speaker and a mixer and one cable going between them. And so there's your chain.
So when you get to the mixer, you plug it in, the noise is there, what do you do? Well, generally speaking, a mixer has a bunch of other things connected to it, and if you disconnect each of those things in turn, if the noise stops when you unplug one of them, you know that it's coming in from the connection with that device. If you get through everything and you've got nothing connected to the mixer except for the speaker amplifier powered box and it's still humming, then the noise is being created between the points at which those two devices are connected to power. If one of those devices has a two-pin plug and the other one a three-pin plug, you can conceivably solve that problem by grounding the piece that has only a two-pin plug. When you do that, if the noise goes away, then you have solved the problem to the point that now you don't have that difference in potential between those two devices.
Normally if you ground a device that isn't grounded, it will solve that problem if the problem is related to that ground loop. Now, it can happen that you have a mixer and a bunch of other pieces of gear that are collectively contributing noise, and you can sometimes simplify and eliminate that problem by connecting all of those devices to the same ground source, which is to say the same power strip, to the same extension cord, to the same whatever, so that you don't have multiple ground points because you could have a bad ground on a power strip. You could have any number of things that could happen when you start distributing that power out.
So one thing that's just a good sort of practice to follow is to connect your mixer and all this stuff, all the light drawer stuff, which is to say your mixer, your wireless microphone receiver, your laptop, your whatever, or, you know, maybe like effects boxes and that kind of thing that you've got on your front end. Connect them all to the same power strip. They are never going to draw that much power. And so if you can connect them all to the same ground potential, it'll minimize the chances that they will pick up noise from being plugged into different circuits, different outlets. And I've seen it happen where noise has been eliminated just by moving things to the same ground point and permits done and the noise is gone. Instead of having to hunt down each individual thing and sort that problem out individually and grounding it, you can both process that and just go, here's this, you know, eight-outlet strip, put everything of these eight pieces of stuff that are in my front end into this one strip and everything there will have the same ground potential. It can solve some problems. It's not guaranteed if there's a fundamental problem in one of those pieces of gear. But it doesn't hurt to start there as a sort of standard practice.
I always like the system to be so quiet that when it's on you, nobody even knows. And when you hit that first note, everybody's surprised. It bothers me. No. And to hear a system going, you know, whether it be a guitar amplifier or something that's just humming away in the background, it drives me crazy. So I find that it's important to work your way through these issues and understand what these things are, to keep that noise to an absolute minimum. And the biggest noise that you hear is the background minimum for noise of high-output amplifiers. And you don't hear them if you're having a conversation. So if we can all achieve that kind of signal-to-noise ratio, everybody's experience is just that much better.